1. Field of the Invention
The present invention generally relates to gas generators employed in small rocket engines and, more particularly, is concerned with a dual catalytic/thermal gas generator and generating method which achieves a reduction in catalyst bed pressure drop at any given rate of bedloading.
2. Description of the Prior Art
Small rocket engines of the type utilized in space satellites are generally of a design which employs a catalytic gas generator to convert a liquid propellant, such as hydrazine, into a high-temperature, propulsive power-producing gas. The gas generator has a catalyst bed in communication with the thrust chamber of the engine. The liquid propellant is injected into the catalyst bed where it reacts to produce the high-temperature gas. The gas exits from the catalyst bed and is expanded through a nozzle on the aft end of the chamber to produce thrust.
It is desirable to be able to operate a conventional catalytic gas generator at as high a bedloading rate (mass flow/unit area) as possible since weight, volume and cost are reduced as the ratio of mass flow to unit area increases. However, the bedloading rate is limited by the compressive strength of the catalyst bed of the generator. As the bedloading rate increases, the pressure drop across the bed increases, eventually crushing the bed which results in destruction of the generator and termination of the usefulness of the rocket engine.
In view of the desirability of gas generator operation at highest possible bedloading rates, a need exists for a fresh approach to gas generator design toward the objective of reducing pressure drop across the catalyst bed at any given rate of bedloading.